Slit or spot lamp stereomicroscope

ABSTRACT

A slit or spot lamp microscope of the kind including a slit or spot lamp and a stereomicroscope, both pivotally mounted on a common vertical axis, characterized in that the end portion of the optical system of the lamp comprises essentially two reflectors, which impart a double-bent path to the optical beam casting the slit or spot image onto an object to be examined, so that the beam portion issuing from the reflector positioned last in the said path, that is, the last beam portion, cooperates with the beam portion entering the reflector positioned first in the said path, that is, the antepenultimate beam portion, to determine the point where the cast image of the slit or spot is formed, while a part of the optical system including at least said two reflectors is adapted to swivel about the axis of said antepenultimate beam portion.

sited States Gambs SLIT OR SPOT LAMP STEREOMICROSCOPE [72] inventor: Paul Frederic Marie Gambs, Lyon, France [73] Assignee: Societe Anonyme dite: Gambs S.A., Lyon,

France 22 Filed: Apr. 17,1970

[21] Appl.No.: 29,608

[52] U.S.C| ..351/14 [51] int.Cl. ....A6lb3/l0 [58] FieldofSeareh ..35l/l4;350/39 [56] References Cited UNITED STATES PATENTS 3,519,338 7/1970 Papritz ..351/14X 3,405,994 10/1968 .AltmanetaL. .....351/14 3,433,560 3/1969 Gambs .351/14. 3,533,685 10/1970 Littmanetal. ..351/14 FOREIGN PATENTS 0R APPLICATIONS mm 1,021,88212/1952 France ..351/14 Primary Examiner-David Schonberg Assistant Examiner-Paul A. Sacher Attorney-Waters, Roditi, Schwartz & Nissen [5 7] ABSTRACT A slit or spot lamp microscope of the kind including a slit or spot lamp and a stereomicroscope, both pivotally mounted on a common vertical axis, characterized in that the end portion of the optical system of the lamp comprises essentially two reflectors, which impart a double-bent path to the optical beam casting the slit or spot image onto an object to be examined, so that the beam portion issuing from the reflector positioned lastin the said path, that is, the last beam portion, cooperates with the beam portion entering the reflector positioned first in the said path, that is, the antepenultimate beam portion, to determine the point where the cast image of the slit or spot is formed, while a part of the optical system including at least said two reflectors is adapted to swivel about the axis of said antepenultimate beam portion.

SLIT R SPOT LAMP STEIREQMICROSCOPE The present invention relates to slit or spot projection lamp microscopes such as, for instance, ocular biomicroscopes for examination of the living eye of a patient seated or lying down.

Apparatus of this type enable a given optical plane to be observed in an eye, with a variable degree of magnification, by casting a beam of light of suitable shape onto said eye.

Generally, such apparatus include essentially a light source, or slit lamp, which casts the optical image of a rectangular slit of variable width onto an eye to be observed, and a stereomicroscope, or corneal microscope," which enables the optical plane, thus obtained in the eye to be observed with a variable degree of magnification.

In the case ofa patient seated, the slit lamp and the corneal microscope are adapted to be moved along horizontal arcs having a common center lying on a theoretical vertical axis passing through the eye to be observed, so as to enable the latter to be examined at various angles.

More particularly, it is advantageous to vary the angle of vertical incidence of the optical plane obtained in the eye, while not modifying the position of the slit image cast thereon. Various methods have hitherto been employed to achieve this result, but they are not fully satisfactory, because they are too complicated, or because the angle of incidence is restricted constructional requirements,

As regardssurgical or, industrial microscopes, it is advanta'geous for the user to be able readily to vary the incidence of the light beam, although, in such cases, a common axis passing through the point observed, and normal to the axis of observation, cannot be used for pivotally mounting the lighting system and the microscope. Attempts have been made for achieving this result by using arc-shaped slideways, but the latter are cumbersome and uneasy to use, so-that most of the present apparatus are unvariable incidence devices.

The object of the presentinvention is to obviate such drawbacks. To this end, it provides a slit or spot lamp microscope, the construction of which only requires a few additional members, which. is comparatively unexpensive, and easy to assemble and adjust, wherein the variation of the angle oflight incidence is limited only by utilization factors.

A slit or spot lamp microscope according to the invention is 7 characterized in that the end portion of the optical system of the slit or spot lamp comprises essentially two reflectors, which impart a double-bent path to the optical beam casting the slit or spotonto an object to be examined, so that the last .portion of said optical beam, that is, that issuing from the reflector positioned last with respect to said path, cooperates with the antepenultimate portion of said optical beam, that is, that entering the reflector positioned first with respect to the path, to determine the point where the cast image of the slit or spot is formed, while a part of the optical system, which includes at least said two reflectors, is adapted to swivel about the axis ofsaid antepenultimate portion ofthe optical beam.

Thus, by rotating the optical system carrying the two end reflectors for the slit or spot lamp, the angle of incidence of the last portion of the optical beam can be varied continuously with respect to any stationary axis of observation, within certain limits, without the position of the cast image of the slit or spot being modified.

According to a preferred embodiment of the invention, the two reflectors are carried by a bent tube, one of the limbs of which, to wit, that through which the optical beam casting the slit or spot passes first, is housed in the end portion ofthe lamp frame, and is adapted to swivel about its longitudinal axis, the said limb being oriented in a manner such that its above-mentioned axis merges into the light beam portion emitted by the lamp, the first reflector carried by the tube inside the bent portion thereof being positioned in a manner such that the penultimate beam portion reflected by said first reflector merges into the axis of the second limb of the bent tube, the said second tube carrying at its free end a projection lens, on the one hand, and the second reflector, on the other hand, which second reflector stands at an angle such to said penultimate beam portion that the last beam portion reflected by said second reflector cooperates with the extension of the antepenultimate portion of the optical beam, that is, with the ex tension of the axis of rotation of the bent tube, to determine the point where the cast image of the slit or spot is formed, and where the object to be examined lies.

In the case where the invention is applied to a slit lamp biomicroscope intended for examining. the eye of a patient seated, the presence of the tube of the device enabling the vertical incidence of the slit image to be modified, prevents in practice using a conventional barrel magnification modifier for the stereomicroscope. In such a case, it is advantageous for the biomicroscope to be provided with a stereomicroscope including a magnification modifier consisting essentially 'of a pair of stationary lenses having their own magnifying power, and one or more pairs of additional optical devices including each a converging element and a diverging element, which additional devices are disposed on a drum, the axis of which is transverse to the optical axes. In order, however, not to increase the distance between the eye to be observed and that of the observer, while maintaining the convergence of the two optical axes, the pair of stationary lenses is disposed inside said drum, the rotation of which locates on each of the two converging axes, respectively, forward and rearward of the stationary lenses, alternately, either empty openings to obtain the own magnifying power of said stationary lenses, or the pair of elements of said pairs of additional optical systems, which combine then with the stationary lenses to produce other magnifying powers, without the focusing plane of the stereomicroscope being modified.

As a result, the lenses of the optical devices of each halfmicroscope constituting the stereomicroscope have fully symmetrical revolutions about the optical axes of said halfmicroscopes, which makes it possible to match wide input and output lenses in the optical devices with a good optical correction, without resorting to complex combinations prejudicial to the transparence of the optical devices, and without increasing the cost price.

The invention will now be described in further detail, for a better understanding thereof, with reference to the accompanying diagrammatic drawings, which illustrate, by way of nonlimiting examples only, two preferred embodiments of the slit or spot lamp microscope of the invention. In the drawings:

FIG. 1 is a side view, in axial section, of a slit lamp biomicroscope for examining the eye of a patient seated, said biomicroscope being in a position at which the angle of vertical incidence of the cast light beam to the optical axis of observation is zero;

FIG. 2 is a partial view, similar to FIG. 1, showing the arrangement for varying the angle of vertical incidence, said arrangement being in an intermediate position;

FIG. 3 is a partial view, similar to FIG. 2, showing said arrangement in its position providing a maximum angle;

FIG. 4 is a top sectional view along line 4-4 in FIG. 1, showing the arrangement of the optical axes in the stereomicroscope;

FIG. 5 is a partial side view, in axial section, of the lighting device in a slit lamp biomicroscope intended for examining the eye of a patient lying down, that is, a surgical biomicroscope.

Referring now to FIGS. 1 to 4 of the drawings, they show an ocular biomicroscope comprising essentially a slit lamp 1, and a stereomicroscope 2, adapted to swivel on a common vertical spindle 3.

The slit or spot lamp 1 includes essentially, in a manner known per se, a light source 4, the rays of which are guided by a condensing system consisting of lenses 5, 6, 7, two reflectors 8, 9, imparting the required path to the optical beam 10, a slit arrangement 12, and a slit casting system including a collecting lens 13, above which a reflector l8 deflects the light beam 10 towards the point 25, where the eye to be observed should be placed.

The embodiment being described includes also three members which are optional, to wit, a flash source 15 intended for taking photographs in a known manner, if required, a condenser l6, and a reflector 17 for combining the light of said flash with the beam 10.

According to the invention, the slit or spot lamp 1 includes, besides, a device disposed downstream of the reflector l8, and including two reflectors 19, 20, a lens 14 being incorporated in said device.

The reflectors l9 and 20 compel the beam 10 to describe a double bend comprising the beam portions 10a, 10b, 10c.

The lens 14 and the reflectors 19, 20, are carried by a bent tube 22, a limb 22a of which is disposed so as to have its axis merging into the beam portion 10c reflected by the reflector 18.

The reflector I9 is disposed inside the tube 22 at the bent portion of the latter, in a manner such that the beam portion 10b reflected thereby merges into the axis of the second limb 22b ofthe tube 22.

The lens 14 is secured to the free end of the limb 22b of the tube 22, while a support 23 on said end carries the reflector 20, which reflects the beam portion 10a towards the point 25.

The device just described is intended to be mounted at the upper part of the frame of the slit or spot lamp, so as to be able to swivel about the axis of the limb 22a of the tube 22.

Furthermore, the reflectors I9, 20, are disposed in a manner such that, after being reflected by the reflector 20, the last portion 10a of the optical beam 10, by which the image of the slit 12 is cast, combines with the extension of the antepenultimate beam portion 10c at the point 25, which point in turn lies on the extension of the axis of the common vertical spindle 3 on which the slit lamp I and the stereomicroscope 2 are pivoted.

As can be seen from FIGS. 1, 2, 3, rotating the tube 22 and, consequently, the reflectors 19, 20, about the beam portion Ic, does not involve any shifting of the cast image of the slit, since said image is formed at 25 on the extension of the axis of rotation of said tube 22. On the other hand, such a rotation of the tube 22 allows varying substantially the angle ofincidence ofthe last beam portion 100 with respect to a fixed axis of observation 26.

As a matter of fact, the beam portion a acts in rotation as the generatrix of a cone which it describes, the axis of said cone being constituted by the extension of the antepenultimate beam portion 10c.

As can be clearly seen from FIGS. 1 and 3, the maximum variation of the angle ofincidence is thus equal to the angle at the apex of the cone described, that is, in the present instance, 50, while the angle between the extension of the beam porlion I0c constituting the axis of rotation, and the beam portion 100 rotating thereabout, is a 25 angle.

As a matter of fact, in the above example, the beam portion 10c reflected by the reflector I8 is at a 25 angle to the optical axis ofobservation 26, the angle ofthe tube 22 is 115, and the beam portions 10a and 10b are at an angle of 90 to each other.

A greater variation of the angle ofincidence would, besides, be useless, due to the presence of the upper and lower eyelids ofthe eye under observation.

The rotation of the device causes also the horizontal incidence of the beam portion 10a to vary with respect to the axis of observation 26.

The value of said horizontal incidence is zero at the two extreme positions of the device, as shown in FIGS. 1 and 3, and is at its maximum at the intermediate position of said device, as shown in FIG. 2. The resulting variation magnitude is 25 on either side of the axis of observation 26. Should this variation of the angle of incidence not be desired, it may be readily compensated by the usual adjustments of the biomicroscope, by rotating the slit lamp 1, or the stereomicroscope 2 about the common vertical spindle 3.

The stereomicroscope 2, which is intended to observe the optical section resulting from the image of the slit 12 being cast onto an eye, is of the type having convergent optical axes, and includes essentially, in a manner known per se,

a pair of stationary lenses 27, 28, having a medium magnifying power,

5 an optional photographic device 29, provided with a reflector 30, which directs a portion of the light beam towards a sensitive surface 32,

a pair of erecting prisms 33, 34,

a pair ofeyepieces 35, 36,

a rotary drum 37 having a horizontal axis transverse to the general axis of the stereomicroscope.

Said drums 37 includes two pairs of empty openings 38, 39 two pairs of divergent doublets 40, 42, and two pairs of convergent doublets 43, 44, all in diametrally opposite relationship.

In the present biomicroscope, the stationary lenses 27, 28, are disposed inside the drum 37. In this way, varying the magnification of the image observed is obtained by rotating the drum 37 about its axis by means of the handles 45, 46.

In order to obtain a medium magnification, a fairly accurate ratchet device stops the drum at a position such that the empty openings 38, 39, are centered on the converging optical axes 47, 48, respectively, as shown in FIG. I. To obtain lower or higher magnifications, the drum 37 is stopped at each end of its revolution by means of stops (not shown), which are accurately adjustable.

In its position of lower magnification, the drum 37 located the divergent doublets 40 between the object being examined, that is, an eye, and the stationary lenses 27, 28, while the convergent doublets 43 lie then between the said stationary lenses 27, 28, and the erecting prisms 33,34.

In its position of higher magnification, the drum 37 locates the convergent doublets 44 between the eye to be observed and the stationary lenses 27, 28, and the divergent doublets 42 between the said stationary lenses and the erecting prisms 33, 34.

FIG. 5 illustrates the invention as applied to a surgical microscope, that is, a biomicroscope used for examining the eye ofa patient lying down. In said Figure, only the slit lamp of a surgical microscope is shown, since said lamp must be integral with the microscope in order to follow the movements and the sharpness focusing thereof. Such integrality is also advantageous, in a more general way, to ensure the centering of the lighted area in the field observed, or conversely. To this end, the lighting device or slit lamp is connected to the microscope by a pivoted arm 51, which is mounted, together with the arm (not shown) supporting the microscope, on a vertical axis 52 merging into the axis of sight of the microscope. Said axis 52 passes thus through the eye 53 of a patient.

The lighting device includes thus a light source 54, a condensing system 55, a slit arrangement 56 pivotally mounted in 55 bearings 57 carried by the arm 51, a lens 58 casting the image of the slit 56 onto the point 53, and a system including two reflectors 59, 61, carried by a tube 62 pivotally mounted about the light beam 63 of the slit lamp located above the said tube 62.

The tube 62 may therefore be compared with the tube 22 of the ocular biomicroscope described with reference to FIGS. 1 to 4. It deflects thus the antepenultimate beam 63 twice in succession, that is, as a penultimate beam 64 and an ultimate beam 65, the latter cooperating with the extension of the antepenultimate beam 63 to form the point 53 onto which the image of the slit 56 is cast.

As in the previous example, it is thus possible to modify the angle ofincidence of the ultimate beam 65 with respect to the axis 52 by rotating the tube 62 about the axis 63, which in- 70 cidence may vary by an angle equal to twice the angle formed by the beams 63 and 65. When the tube 62 is in either of its extreme positions, that is, that shown in FIG. 5, or that it occupies after rotating by 180 with respect to its said position in FIG. 5, the incidence of the beam 65 includes no tangential component.

On the other hand, in all intermediate positions of the tube 62, said incidence includes a tangential component, which can be readily compensated by rotating the arm 51 about the axis 52 by a suitable angle. This rotation results in an identical rotation of the slit 56, which it is possible to compensate by swiveling the slit system 56 in the opposite direction.

As will be readily seen from FIG. 5, the arrangement enabling the incidence of the light beam to be varied, does not affect appreciably the space taken up by the apparatus.

Obviously, the invention is by no means confined to the embodiments thereof described in the foregoing by way of examples only; on the contrary, it includes all the possible alternative embodiments which will be apparent to those skilled in the art, and are within the spirit and scope of the appended claims.

What is claimed is:

l. A projection lamp microscope for casting an image hav-' ing a variable incidence onto an object to be examined, comprising a projection lamp, a stereomicroscope for observing said image with a variable magnification, means mounting said lamp and said stereomicroscope for pivotal motion about a common vertical axis, said lamp having an optical system, the end portion of the optical system including two reflectors, said reflectors imparting a double-bent path to an optical beam casting the variable incidence image, the final portion of said bent optical beam issuing from the reflector positioned last with respect to said beam path cooperating with the antepenultimate portion of said optical beam entering the other reflector positioned first with respect to said path, so as to determine the point upon which the cast image of the optical beam is formed, and means mounting a portion of the optical system including at least said two reflectors for pivotal motion about the axis of said antepenultimate portion of the optical beam.

2. A stereomicroscope as claimed in claim 1, comprising a bent tube carrying the two reflectors, said bent tube having a tion reflected by said first reflector merges into the axis of the second limb of the bent tube, said second limb carrying at its free end a projection lens and the second reflector, said second reflector being positioned at an angle relative to said penultimate beam portion whereby the last beam portion reflected by said second reflector cooperates with the extension of the antepenultimate portion of the optical beam defining the extension of the axis of rotation of the bent tube, so as to determine the point where the cast image is formed and the location of the object being examined.

3. A stereomicroscope as claimed in claim 1, wherein said microscope is of the kind used for eye testing, a rotatable drum connected to said stereomicroscope, of said drum including lens means mounted thereon for varying the magnifying power of the stereomicroscope, said drum having a horizontal axis transverse to the optical axes of the stereomicroscope, a pair of stationary lenses on said stereomicroscope optically associated with said lenses on the drum, said stationary lenses being disposed inside the rotary drum, and additional optical elements in said drum for varying magnifying power of the stationary lenses.

4. A stereomicroscope as claimed in claim 3, said stereomicroscope comprising a pair of half-microscopes, said lenses of the optical system for each half-microscope being mounted for rotation symmetrically about the optical axes of said half-microscopes. 

1. A projection lamp microscope for casting an image having a variable incidence onto an object to be examined, comprising a projection lamp, a stereomicroscope for observing said image with a variable magnification, means mounting said lamp and said stereomicroscope for pivotal motion about a common vertical axis, said lamp having an optical system, the end portion of the optical system including two reflectors, said reflectors imparting a double-bent path to an optical beam casting the variable incidence image, the final portion of said bent optical beam issuing from the reflector positioned last with respect to said beam path cooperating with the antepenultimate portion of said optical beam entering the other reflector positioned first with respect to said path, so as to determine the point upon which the cast image of the optical beam is formed, and means mounting a portion of the optical system including at least said two reflectors for pivotal motion about the axis of said antepenultimate portion of the optical beam.
 2. A stereomicroscope as claimed in claim 1, comprising a bent tube carrying the two reflectors, said bent tube having a first limb through which the optical beam casting the image initially passes, and a second limb connected to said first limb a frame for said lamp, said limbs being housed in the upper part of the lamp frame so as to be pivotable about its longitudinal axis, said first limb further being oriented in a manner such that its said axis merges into the light beam portion emitted by the lamp, the first reflector being carried on the bent portion of the tube being positioned so that the penultimate beam portion reflected by said first reflector merges into the axis of the second limb of the bent tube, said second limb carrying at its free end a projection lens and the second reflector, said second reflector being positioned at an angle relative to said penultimate beam portion whereby the last beam portion reflected by said second reflector cooperates with the extension of the antepenultimate portion of the optical beam defining the extension of the axis of rotation of the bent tube, so as to determine the point where the cast image is formed and the location of the object being examined.
 3. A stereomicroscope as claimed in claim 1, wherein said microscope is of the kind used for eye testing, a rotatable drum connected to said stereomicroscope, of said drum including lens means mounted thereon for varying the magnifying power of the stereomicroscope, said drum having a horizontal axis transverse to the optical axes of the stereomicroscope, a pair of stationary lenses on said stereomicroscope optically associated with said lenses on the drum, said stationary lenses being disposed inside the rotary drum, and additional optical elements in said drum for varying magnifying power of the stationary lenses.
 4. A stereomicroscope as claimed in claim 3, said stereomicroscope comprising a pair of half-microscopes, said lenses of the optical system for each half-microscope being mounted for rotation symmetrically about the optical axes of said half-microscopes. 